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III. SURFACE WATER <br />GAUGING STATIONS <br />Figure 1 shows the continuous streamflow records for Trout Creek at TR-a and <br />TR-b. The graphs showing the results of the gauging stations along Trout Creek <br />indicate that the monitoring program is being placed on-line early enough in the <br />year to record flow prior to the peak runoff period for each year. The individual <br />data points show the monthly average flows and give some indication of the <br />variability between mild winters (winters of less snow accumulation) and harsh <br />winters. The graph showing 1995-1997 data indicates a slight variation in the total <br />streamflow between 1995, 1996 and 1997. The 1988-1997 graph suggests that 1999 was <br />the driest winter over the past decade and 1993 was the wettest for the watershed. <br />The flow record for 1997 shows the peak flow to have occurred in June as it <br />did during 1988, 1989, 1990, 1991, 1993 and 1995. The later peak flows for these <br />years were probably due to more harsh winters or the on-set of warmer temperatures <br />occurring later in the spring. The 1997 record suggests that snowmelt from the mine <br />area was fairly rapid when it occurred as evidenced by the flow differential between <br />TR-a and TR-b in the early part of the year. In previous years, snowmelt appears to <br />have been more uniform throughout the Trout Creek watershed. <br />The stage/flow rating curve for TR-a was reviewed in June of 1999 to ensure <br />its continued accuracy. Sufficient differences in the channel cross-section at TR-a <br />were noted during the review to warrant development of a new stage/flow rating <br />curve. Over the 1999-1995 seasons, a total of five cross-sections were developed <br />and compared to ensure channel stability. An averaged cross-section was then <br />developed to compute a stage/rating curve. The stage rating curve data covered <br />flows ranging from approximately two cfs to 85 cfs. The equation and rz for the <br />3.1636 <br />curve are as follows: y = 13.817x where y = flow in cfs and x = depth of flow; <br />r~ = 0.96. During 1997, cross-section measurements were taken to confirm that the <br />channel configuration had remained stable during the past annual monitoring period. <br />Flow data for TR-b consists of both instantaneous flow and continuous flow <br />measurements. The flow data presented in Figure 1 consists only of information <br />derived from continuous flow records. Instantaneous flow measurements obtained <br />between 1989 and June 1999 for this location are provided in Appendix A. Prior to <br />that time, instability of the stream channel caused by a 1989 flood precluded the <br />installation of any type of monitoring station in the vicinity. <br />Instantaneous flow measurements were recorded at TR-b during 1989 in <br />conjunction with water quality samples taken at TR-D, except for the October <br />• sampling period. Between the sampling periods of September and October in 1989, <br />beaver activity both above and below TR-b occurred causing the location of TR-b to <br />2 <br />